Stablehands in NSW will be subject to drug testing under a new rule to come into effect on December 1.

The new rule comes in the wake of the Gai Waterhouse-trained horse Love You Honey testing positive to cocaine earlier this year.

Under the current rule only jockeys and trackwork riders are tested for drugs.

Racing NSW chief steward Ray Murrihy said the broadening of the rule to include stable staff had been in the pipeline for some time but the need for change was highlighted by the Love You Honey case.

The Waterhouse-trained horse tested positive to cocaine after she raced at Gosford in April with stewards and the Racing NSW Appeal panel agreeing it came as the result of contamination by a stablehand.

"The change to the rule was always going to happen but it was highlighted by the Love You Honey case," Murrihy said.

"Stewards met with the Trainers' Association and we agreed it should be introduced.

"There is the obvious O H and S (Occupational Health and Safety) issue where nobody wants someone handling horses if they are under the influence of drugs.

"The new rule means that anyone handling horses will be subject to testing."

Waterhouse caused a furore at the initial inquiry when she suggested cocaine use was rampant in the eastern suburbs of Sydney.

She was found guilty of presenting a horse to race with a prohibited substance in its system under the rules of racing which state the trainer beats ultimate liability.

However a $15,000 penalty imposed was overturned by the appeal panel which said she had done more than most to ensure the security of her stable.

Waterhouse also called for the introduction of threshold levels to recreational drugs.

The new rule will make it an offence for any person to have a banned substance in their system when employed by or assisting a trainer and present on any racecourse, training centre or registered stable.